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In this research,a lucunary Keggin structure,[PMo_2W_9O_(39)]~(7-) was selected as an efficient homogenous catalyst for degradation of an azo dye(direct blue 71) and a simple method was developed for degradation of DB71.The method is based on the oxidation of azo dye in the presence of a lucunary Keggin form of polyoxometalates,K_7[PMo_2W_9O_(39)]? 19H_2O,as a homogenous catalyst at room temperature.The reaction is monitored spectrophotometrically by measuring the absorbance of dye atλ=585 nm.Some parameters including concentration of catalyst,concentration of H_2O_2,pH and reaction time were investigated and optimized. Results show that K_7[PMo_2W_9O_(39)]? 19H_2O is more efficient in the presence of hydrogen peroxide.Degradation of dye in the presence of the catalyst and H_2O_2 could lead to the disappearance approximately 65%of dye after 60 min.But degradation for the same experiment performed in the absence of catalyst or in the absence of H_2O_2 was 22%or 5%respectively.Approximately 87% azo dyes has been eliminated after 90 min in the presence of catalyst,H_2O_2 and optimize conditions(0.6 g/L of K_7[PMo_(2-) W_9O_(39)H_9H_2O,0.08 mol/L hydrogen peroxide and room temperature).
In this research, a lucunary Keggin structure, [PMo_2W_9O_ (39)] ~ (7-) was selected as an efficient homogenous catalyst for degradation of an azo dye (direct blue 71) and a simple method was developed for degradation of DB71. method is based on the oxidation of azo dye in the presence of a lucunary Keggin form of polyoxometalates, K_7 [PMo_2W_9O_ (39)] · 19H_2O, as a homogenous catalyst at room temperature. The reaction is monitored spectrophotometrically by measuring the absorbance of dye atλ = 585 nm. Some parameters include concentration of catalyst, concentration of H 2 O 2, pH and reaction time were investigated and optimized. Results show that K_7 [PMo_2W_9O_ (39)] 19H_2O is more efficient in the presence of hydrogen peroxide. the presence of the catalyst and H_2O_2 could lead to the disappearance about 65% of dye after 60 min. Baut degradation for the same experiment performed in the absence of catalyst or in the absence of H_2O_2 was 22% or 5% respectively. Approxima tely 87% azo dyes have been eliminated after 90 min in presence of catalyst, H 2 O 2 and optimize conditions (0.6 g / L of K_7 [PMo_ (2-) W_9O_ (39) H_9H_2O, 0.08 mol / L hydrogen peroxide and room temperature) .